Golf ball having high surface friction

ABSTRACT

A golf ball comprising a core and a cover, wherein an outermost surface of the golf ball has a coefficient of friction of greater than 0.6.

FIELD OF THE INVENTION

[0001] The present invention relates to golf balls and, moreparticularly, to a golf ball outermost surface having specific frictionand gloss properties. The outermost surface of the golf ball may be theouter surface of a coating layer or, alternatively, the outer surface ofan outer cover layer.

BACKGROUND OF THE INVENTION

[0002] The United States Golf Association (“USGA”) provides five (5)regulations to keep golf balls consistent. Specifically, the golf ballmust weigh no more than 1.62 ounces and measure no less than 1.68 inchesin diameter. The initial velocity of the ball as tested on a USGAmachine at a set club head speed must not exceed 255 ft/sec. The overalldistance of the ball as tested with a USGA specified driver at 160ft/sec and a 10-degree launch angle must not exceed 296.8 yards.Furthermore, the ball must pass a USGA-administered symmetry test.Within the confines of these regulations, other performancecharacteristics of the ball, including distance, durability, feel, spin,sound, and the like may be modified through alterations in materialcompositions, constructions, diameters and/or thickness, and surfaceconfigurations of various portions of the ball, such as the core, thecover, intermediate layer(s) disposed between the core and the cover,and coating layer disposed about the cover. Other physical, mechanical,chemical, and/or optical properties of the portions, including colorstability, compression, density, flexural modulus, gas or vaporpermeability, hardness, stiffness, tear resistance, weight, gloss, andthe like may also be affected by these alterations.

[0003] Traditionally, it is recognized that the back spin imparted to agolf ball when hit with a golf club provides in part the aerodynamiclift that makes the ball airborne and prolongs its flight time, as wellas enables the ball to stop on a green. There are two force componentsacting on the golf ball during impact: a normal force at a right angleto the club face and a tangential force parallel to the club face. Theratio of the tangential force to the normal force represents thecoefficient of friction (“COF”) of the ball on the club face which, asknown to a skilled artisan, has a direct effect on the amount of spinimparted to the ball. This effect is more prominent in irons of higherlofts. It is feasible, therefore, to impart specific properties to theoutermost surface of the golf ball and achieve desirable performancecharacteristics.

[0004] The golf ball of the present invention, as disclosed hereinbelow, has a COF of greater than 0.6. This may be brought about by usinga high COF material composition for the outer cover layer, if the outersurface of the outer cover layer is the outermost surface of the golfball. In a conventional golf ball employing materials such as balata,Surlyn®, or polyurethane as cover materials, a protective coating layerhaving a relatively high gloss (60° gloss being greater than about 80)is typically applied to encapsulate the golf ball cover and constitutesthe only ball portion that makes direct contact with the club face. Assuch, it is desirable to dispose a high COF coating layer of superiormar and abrasion resistance and weatherability about the golf ball, toelevate the ball COF, enhance its durability and aesthetic appeal, andselectively optimize performance parameters such as spin, drag, andfeel.

SUMMARY OF THE INVENTION

[0005] The present invention is directed to a golf ball having a highCOF outermost surface. The high COF of the outermost surface ispreferably greater than 0.6, more preferably greater than about 0.7, andmost preferably about 0.8 to about 1.5. The outermost surface ishydrophobic, having a 60° gloss of preferably at least about 3, morepreferably at least about 50, and most preferably about 80 to about 95.The outermost surface can be the outer surface of a cover or an outercover layer, but is preferably the outer surface of a coating layer.

[0006] The coating layer can be translucent, transparent, or pigmented,having a thickness of about 0.0001 inches to about 0.01 inches. Thecoating layer has a Sward hardness of preferably less than about 20,more preferably less than about 10, and most preferably less than about5. The coating layer has a cross hatch adhesion of about 90% to about100%, and a pencil hardness of about 3 B to about 3H. The coating layeris typically formed from a liquid reactive material, having a solidcontent by weight of at least about 40%.

[0007] In one embodiment, the coating layer is formed from atwo-component thermoset polyurethane. The polyurethane is preferablysubstantially saturated. The polyurethane may blend in a variety ofadditives, such as an UV absorber, a hindered amine light stabilizer, anantioxidant, an optical brightener, a filler, a coupling agent, acolorant, or a combination thereof.

[0008] The golf ball cover of the present invention can be asingle-piece cover or a multi-layer cover comprising an outer coverlayer and one or more inner cover layers. The single-piece cover or theouter cover layer is formed from at least one polymer material known toone skilled in the art. Suitable polymer materials for the coverinclude, but are not limited to, metallocene-catalyzed polymers,ethylene/acid ionomers, thermoplastic or thermoset polyurethanes, orcombinations thereof. Preferably, the coating layer is contiguous withthe cover or the outer cover layer.

[0009] The high COF outermost surface as disclosed herein provides thegolf ball with certain unique performance characteristics. Such golfballs display small changes in driver spin rate, but large changes infull wedge spin rate and half wedge spin rate. Specifically, the highCOF golf balls have a spin rate change of less than about 15% whenstruck with a standard driver at a speed of about 160 ft/sec, and theirlaunch angle is not changed much either. When struck with a full wedgeat a speed of about 95 ft/sec, the high COF golf balls demonstrate anelevated launch angle and a spin rate reduction of at least about 5%.When struck with a half wedge at a speed of about 53 ft/sec, the highCOF golf balls demonstrate an elevated launch angle and a spin ratereduction of at least about 10%. The reductions in full wedge and halfwedge spin rates can be as high as about 60% or more.

[0010] To impart the golf ball with a high COF outermost surface, amaterial is used to form an outermost solid layer about a golf ballprecursor. The material is first deposited onto the golf ball precursorthrough spraying, dipping, spin coating, or flow coating to form asubstantially even layer of the material with a wet thickness of lessthan about 0.05 inches. Then the wet layer is cured into the outermostsolid layer having a dry thickness of at least about 0.001 inches. Theoutermost solid layer is a coating layer or a cover layer.

Definitions

[0011] As used herein, the term “polyahl” or “reactive polyahl” refersto any one compound or a mixture of compounds containing a plurality ofactive hydrogen moieties per molecule. Illustrative of such activehydrogen moieties are —OH (hydroxy group), —SH (thio group), —COOH(carboxylic acid group), and —NHR (amine group), with R being hydrogen,alkyl, aryl, or epoxy; all of which may be primary or secondary. Theseactive hydrogen moieties are reactive to free isocyanate groups, formingurethane, urea, thiourea or corresponding linkage depending on theparticular active hydrogen moiety being reacted. The polyahls may bemonomers, homo-oligomers, co-oligomers, homopolymers, or copolymers.Oligomeric and polymeric polyahls having at least one NCO-reactive groupon each terminal of a backbone are typically employed as the softsegment in reaction products such as polyureas and polyurethanes.Depending on the terminal groups, the oligomeric and polymeric polyahlsmay be identified as polyols (with —OH terminals only), polyamines (with—NHR terminals only), or amino alcohols (with both —OH and —NHRterminals). Such polyahls with a relatively low molecular weight (lessthan about 5,000), and a wide variety of monomeric polyahls, arecommonly used as curing agents. The polyahls are generally liquids orsolids meltable at relatively low temperatures.

[0012] As used herein, the term “saturated” or “substantially saturated”means that the compound or material of interest is fully saturated(i.e., contains no double bonds, triple bonds, or aromatic ringstructures), or that the extent of unsaturation is negligible, e.g. asshown by a bromine number in accordance with ASTM E234-98 of less than10, preferably less than 5.

[0013] As used herein, the term “percent NCO” or “% NCO” refers to thepercent by weight of free, reactive, and unreacted isocyanate functionalgroups in an isocyanate-functional molecule or material. The totalformula weight of all the NCO groups in the molecule or material,divided by its total molecular weight, and multiplied by 100, equals thepercent NCO.

[0014] As used herein, the term “equivalent” is defined as the number ofmoles of a functional group in a given quantity of material, andcalculated from material weight divided by equivalent weight, the laterof which refers to molecular weight per functional group. Forisocyanates the equivalent weight is (4210 grams)/% NCO; and forpolyols, (56100 grams)/OH#.

[0015] As used herein, the term “flexural modulus” or “modulus” refersto the ratio of stress to strain within the elastic limit (measured inflexural mode) of a material, indicates the bending stiffness of thematerial, and is similar to tensile modulus. Flexural modulus, typicallyreported in Pascal (“Pa”) or pounds per square inch (“psi”), is derivedin accordance to ASTM D6272-02.

[0016] As used herein, the term “water vapor transmission rate” (“WVTR”)refers to the mass of water vapor that diffuses into a material of agiven thickness per unit area per unit time at a specific temperatureand humidity differential. Standard tests for WVTR include ASTM E96-00.

[0017] As used herein, the term “material hardness” refers toindentation hardness of non-metallic materials in the form of a flatslab or button as measured with a durometer. The durometer has aspring-loaded indentor that applies an indentation load to the slab,thus sensing its hardness. The material hardness can indirectly reflectupon other material properties, such as tensile modulus, resilience,plasticity, compression resistance, and elasticity. Standard tests formaterial hardness include ASTM D2240-02b. Unless otherwise specified,material hardness reported herein is in Shore D. Material hardness isdistinct from the hardness of a golf ball portion as measured directlyon the golf ball (or other spherical surface). The difference in valueis primarily due to the construction, size, thickness, and materialcomposition of the golf ball components (i.e., center, core and/orlayers) that underlie the portion of interest. One of ordinary skill inthe art would understand that the material hardness and the hardness asmeasured on the ball are not correlated or convertible.

[0018] As used therein, the term “compression,” also known as “ATTIcompression” or “PGA compression,” refers to points derived from aCompression Tester (ATTI Engineering Company, Union City, N.J.), a scalewell known in the art for determining relative compression of aspherical object. Compression is a property of a material as measured ona golf ball construction (i.e., on-ball property), not a property of thematerial per se.

[0019] As used herein, the term “coefficient of restitution” or “COR”for golf balls is defined as the ratio of a ball's rebound velocity toits initial incoming velocity when the ball is fired out of an aircannon into a rigid vertical plate. The faster a golf ball rebounds, thehigher the COR it has, the more the total energy it retains when struckwith a club, and the longer the ball flies. The initial velocity isabout 50 ft/sec to about 200 ft/sec, and is usually understood to be 125ft/sec, unless otherwise specified. A golf ball may have different CORvalues at different initial velocities.

[0020] The term “about,” as used herein in connection with one or morenumbers or numerical ranges, should be understood to refer to all suchnumbers, including all numbers in a range.

DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention is primarily directed to a new outermostsurface for a golf ball. In a conventional golf ball, the portion thatmakes contact with a golf club in play is its outermost surface, whichis typically formed form a coating layer disposed about the cover of theball. The coating layer serves to protect the ball, the identifyingindicia, and any paint layers; to enhance abrasion and shear resistanceof the cover; and to add a pleasing, high gloss appearance to the ball.The coating layer may comprise a clear or pigmented primer coat and atranslucent, transparent, clear, or pigmented topcoat, although forcertain applications a single topcoat may suffice. The primer coat isapplied to promote adhesion or to smooth surface roughness of the coverprior to application of the topcoat(s). Coating compositions areconventionally free of pigmentation and are water white. However, theymay contain small amounts of dye, pigment, and optical brighteners solong as they still allow for a bright ball cover. Various identifyingindicia may be applied either directly upon or alternatively upon thecover, the primer coat, or the topcoat.

[0022] The coating layer of the present invention preferably has a softluxurious feel, capable of providing a high COF to the golf ball offcertain clubs (i.e., a putter), without adversely affecting velocity orother desirable properties of the golf ball off other clubs (i.e., adriver). The material forming the coating layer has a Sward hardness ofpreferably less than about 20, more preferably less than about 10, andmost preferably less than about 5. Sward hardness is tested according toASTM D2134-66. The material also has a COF of preferably greater than0.6, more preferably at least about 0.7, and most preferably from about0.8 to about 1.5. The COF disclosed herein is a static coefficient offriction determined with an inclined plane apparatus (such as aninclinometer) according to ASTM D4518-91, titled “Standard Test Methodsfor Measuring Static Friction of Coating Surfaces.” Static friction isthe force that holds back a stationary object up to the point that itjust starts moving. Thus, the COF concerns the force restricting themovement of the stationary object with a relatively smooth, hardsurface, such as a polished metal surface, resting on a coating layer.The inclined plane apparatus consists of a horizontal stationary platerigidly mounted to a hinged incline plate attached to an actuator.Movement of the actuator arm permits adjustable inclined planes of up to90°. A dry thin coating layer (less than about 0.01 inch in thickness)is formed on the hinged plate resting at 0° (in a horizontal position).At ambient temperature, a 2″×1.5″×1.5″ polished aluminum block of 194.49g is placed on the coating layer, and the hinged plate moves slowly toraise the incline gradually from 0°, until the aluminum block juststarts to slide. The angle of friction at that inclined position, alsoreferred to as slide angle and angle of slippage, is recorded. Thisprocedure is repeated ten (10) times to provide an averaged angle offriction θ. The COF is numerically equivalent to the tangent of thisangle of friction: μ_(static)=tan θ. Corresponding to the preferred COFranges described above, the coating layer of the present invention hasan angle of friction of preferably greater than 30°, more preferablyabout 35° to about 65°, and most preferably about 45° to about 60°.Alternative methods and apparatus for COF assessment include thosedisclosed in U.S. Pat. No. 6,016,685, the entirety of which isincorporated by reference herein.

[0023] Besides having a soft feel and a high COF, the coating layer ofthe present invention preferably also has a substantial level of gloss,so that the resulting golf ball has an aesthetically pleasingappearance. The gloss of any surface is dependent on the underlyingmaterial composition, the surface smoothness, and its ability to reflectlight, particularly visible light. Gloss is a measure of specularreflection: the higher the percentage of reflection, the glossier thesurface. The level of gloss is typically measured with a gloss meter,which projects an illumination beam at an angle onto a sample surface,and measures the percentage of reflected light over a small range of thereflection angle that is registered by a detector. The illumination ispreferably near infrared, which is almost impervious to ambient light orthe effect of different colors. The illumination angle is critical,particularly for non-metals (coatings, plastics), because it ispositively correlated to the amount of specular reflection. Thedifference between illumination and reflection is absorbed or diffuselyscattered dependent on the material and its color. The result ofreported by the gloss meter, in Gloss Units of 0 (completelytransparent) to 100 (completely reflective) is normalized not againstthe amount of the incident light, but against the amount of reflectedlight from a black glass standard with a defined refractive index, whichis calibrated to 100 Gloss Units. Measuring standards for gloss includeASTM D523-89, titled “Standard Test Method for Specular Gloss” and ASTMD2457-97, titled “Standard Test Method for Specular Gloss of PlasticFilms and Solid Plastics.” The coating layer of the present inventionpreferably has a 60° gloss of at least about 3, more preferably at leastabout 50, and most preferably about 80 to about 95. In one embodiment,the coating layer has a 20° gloss of preferably at least about 5, morepreferably at least about 30, and most preferably about 70 to about 95.

[0024] The coating layer of the present invention is preferablysubstantially hydrophobic, and has other desirable physical properties,such as a cross hatch adhesion of about 90% to about 100% (based on ASTMD3359-O₂) and a pencil hardness of about 3 B to about 3H (based on ASTMD3363-00). The coating layer preferably has a solid content of greaterthan about 40%, more preferably at least about 60%. These properties areprovided by one-component or two-component chemical systems suitable forthe coating layer, which include, but are not limited to, polyurethane,acrylic, epoxy, vinyl, latex, and the like or combinations thereof.One-component systems are generally made up of minute, polymeric,reacted or partially reacted resinous particles that are suspended ordispersed in one or more solvents. Suitable resins include, but are notlimited to, acid functional resins or unsaturated resins, such asepoxies, acrylics, polyethers, polyesters, polyamides, anhydrides,unsaturated carboxylic acid resins, unsaturated vinyl resins, and otherradical polymerizable materials.

[0025] Typically, a suitable free-radical initiator is used to begin thepolymerization process of forming the particles in the one-componentsystems. The initiator may be a compound or a mixture of compounds,including thermal initiators and photoinitiators. Thermal initiators arepreferably organic peroxides or azo compounds, such as di(t-amyl)peroxide, di(t-butyl) peroxide, dicumyl peroxide, lauryl peroxide,benzoyl peroxide, di(2-t-butylperoxy-isopropyl)-benzene peroxide,1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,2,5-di(t-butylperoxy)-2,5-dimethylhexane,n-butyl-4,4-bis(t-butylperoxy)valerate, t-butyl hydroperoxide, and thelike. Photoinitiators include ultraviolet (“UV”) photoinitiators such asbenzophenones, visible-light photoinitiators, or combinations of two ormore thereof. The compound-based initiators may be present in an amountgreater than about 0.1 parts per hundred of the total resin, preferablyabout 0.1 to about 15 parts, and more preferably about 0.2 to about 5parts. The initiator may also be one or more energy means, such asheating, electron beam irradiation, x-ray irradiation, γ-rayirradiation, UV light irradiation, visible light irradiation, infraredlight irradiation, microwave irradiation, or any other high-energyradiation sources capable of generating reactive free radicals. Curingand subsequent formation of the coating is further facilitated byevaporation of the solvent(s) and/or addition of a curing agent.

[0026] Two-component systems form a coating through a polymerizationreaction of primary reactants upon mixing, optionally accompanied orfollowed by evaporation of the solvent(s). Coatings formed fromtwo-component systems are generally preferred because of good cure atordinary temperatures, formation of strong and stable linkages, andflexibility in choices of reactants. These characteristics makes thecoatings resistant to water and chemical attacks, superior in strengthand durability, and allows a high degree of freedom in designing thecoating with desired physical, chemical, and optical properties.

[0027] Preferably, the coating composition of the present invention is athermoset polyurethane system contains a component A and a component Breactive to each other. Component A comprises a polymer having at leastone isocyanate-reactive functionality, such as a polyahl, and optionallyone or more isocyanate-reactive modifiers. Preferred polyahls includepolyols, polyamines, polymer precursors, or mixtures of two or morethereof. Non-limiting examples of polyols include acrylic polyols,polyester polyols, polyether polyols, polyolefin polyols, polycarbonatepolyols, polyamide polyols, amino alcohols, short oil alkyds, epoxyresins with secondary hydroxy groups, phenolic resins, and polyvinylpolyols. Vinyl resins may be used preferably to promote adhesion.Polymer precursors include radiation-curable monomers, oligomers, andpolymers, such as acrylates, methacrylates, epoxies, and combinations oftwo or more thereof. Polyamines and other polyols disclosed herein forvarious golf ball portions are also suitable for the coating layer.

[0028] Reactive component B comprises at least one isocyanate. Anyisocyanate available to one of ordinary skill in the art is suitable foruse according to the invention. The isocyanate may be organic, modifiedorganic, saturated, aliphatic, alicyclic, unsaturated, araliphatic,aromatic, substituted, or unsubstituted diisocyanate or polyisocyanatemonomers having two or more free reactive isocyanate (“NCO”) groups;isomers thereof; modified derivatives thereof; dimers thereof; trimersthereof; or isocyanurates thereof. The isocyanate may also include anyisocyanate-terminated multimeric adducts, oligomers, polymers,prepolymers, low-free-monomer prepolymers, quasi-prepolymers, andmodified polyisocyanates derived from the isocyanates andpolyisocyanates above. Low-free-monomer prepolymers refer to prepolymershaving free isocyanate monomer levels less than about 0.5 weightpercent.

[0029] In addition to the free reactive isocyanate groups, the suitableisocyanate further comprises at least one cyclic, aromatic, aliphatic,linear, branched, or substituted hydrocarbon moiety R containing from 1to about 20 carbon atoms, such as arylenes, aralkylenes, alkylenes, orcycloalkylenes. When multiple cyclic or aromatic groups are present,linear, branched or substituted hydrocarbons containing from 1 to about10 carbon atoms can be present as spacers between such cyclic oraromatic groups. In some cases, the cyclic or aromatic group(s) may besubstituted at the 2- (ortho-), 3- (meta-), and/or 4- (para-) positions.Substituted groups may include, but are not limited to, halogens, cyanogroups, amine groups, silyl groups, hydroxyl groups, acid groups, alkoxygroups, primary or secondary or tertiary hydrocarbon groups, or acombination of two or more groups thereof. Any and all of theisocyanates disclosed herein may be used alone or in combination of twoor more thereof.

[0030] Preferred isocyanates include diisocyanates (having two NCOgroups per molecule), dimerized biurets or uretdiones thereof,trimerized isocyanurates thereof, and polyisocyanates such as monomerictriisocyanates. Exemplary diisocyanates include, but are not limited to,unsaturated isocyanates such as: p-phenylene diisocyanate (“PPDI,” i.e.,1,4-phenylene diisocyanate), m-phenylene diisocyanate (“MPDI,” i.e.,1,3-phenylene diisocyanate), o-phenylene diisocyanate (i.e.,1,2-phenylene diisocyanate), 4-chloro-1,3-phenylene diisocyanate,toluene diisocyanate (“TDI”), m-tetramethylxylene diisocyanate(“m-TMXDI”), p-tetramethylxylene diisocyanate (“p-TMXDI”), 1,2-, 1,3-,and 1,4-xylene diisocyanates, 2,2′-, 2,4′-, and 4,4′-biphenylenediisocyanates, 3,3′-dimethyl-4,4′-biphenylene diisocyanate (“TODI”),2,2′-, 2,4′-, and 4,4′-diphenylmethane diisocyanates (“MDI”),3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, carbodiimide-modifiedMDI, polyphenylene polymethylene polyisocyanate (“PMDI,” i.e., polymericMDI), 1,5-naphthalene diisocyanate (“NDI”), 1,5-tetrahydronaphththalenediisocyanate, anthracene diisocyanate, tetracene diisocyanate; andsaturated isocyanates such as: 1,4-tetramethylene diisocyanate,1,5-pentamethylene diisocyanate, 2-methyl-1,5-pentamethylenediisocyanate, 1,6-hexamethylene diisocyanate (“HDI”) and isomersthereof, 2,2,4- and 2,4,4-trimethylhexamethylene diisocyanates,1,7-heptamethylene diisocyanate and isomers thereof, 1,8-octamethylenediisocyanate and isomers thereof, 1,9-novamethylene diisocyanate andisomers thereof, 1,10-decamethylene diisocyanate and isomers thereof,1,12-dodecane diisocyanate and isomer thereof, 1,3-cyclobutanediisocyanate, 1,2-, 1,3-, and 1,4-cyclohexane diisocyanates, 2,4- and2,6-methylcyclohexane diisocyanates (“HTDI”), isophorone diisocyanate(“IPDI”), isocyanatomethylcyclohexane isocyanate,isocyanatoethylcyclohexane isocyanate, bis(isocyanatomethyl)cyclohexane(i.e., 1,4-cyclohexane-bis(methylene isocyanate)),4,4′-dicyclohexylmethane diisocyanate (“H₁₂MDI,” i.e.,bis(4-isocyanatocyclohexyl)-methane), 2,4′- and 4,4′-dicyclohexanediisocyanates, 2,4′- and 4,4′-bis(isocyanatomethyl) dicyclohexanes.Dimerized biurets or uretdiones of diisocyanates and polyisocyanatesinclude, for example, unsaturated isocyanates such as uretdiones oftoluene diisocyanates, uretdiones of diphenylmethane diisocyanates; andsaturated isocyanates such as biurets or uretdiones of hexamethylenediisocyanates. Trimerized isocyanurates of diisocyanates andpolyisocyanates include, for example, unsaturated isocyanates such astrimers of diphenylmethane diisocyanate, trimers of tetramethylxylenediisocyanate, isocyanurates of toluene diisocyanates; and saturatedisocyanates such as isocyanurates of isophorone diisocyanate,isocyanurates of hexamethylene diisocyanate, isocyanurates oftrimethyl-hexamethylene diisocyanates. Monomeric triisocyanates include,for example, unsaturated isocyanates such as 2,4,4′-diphenylenetriisocyanate, 2,4,4′-diphenylmethane triisocyanate,4,4′,4″-triphenylmethane triisocyanate; and saturated isocyanates suchas 1,3,5-cyclohexane triisocyanate.

[0031] Isocyanate-terminated oligomers or polymers include anyoligomers, polymers, prepolymers, or quasi-prepolymers having at leasttwo free reactive isocyanate groups as terminal groups, and optionallymore pendant isocyanate groups, on the oligomeric or polymericbackbones. Isocyanate-terminated prepolymers and quasi-prepolymers arewell known to the skilled artisan, and include, but are not limited to,the reaction products of any one or combination of two or more of theisocyanates listed above and any one or combination of two or more ofthe polyahls disclosed herein.

[0032] Among the above-listed isocyanates, all of the saturatedisocyanates display satisfactory light stability when used in golf ballscover layers, and are most preferred in the coating compositions of thepresent invention. Particular isocyanates such as biurets andisocyanurate trimers of hexamethylene diisocyanate may further enhanceadhesion and abrasion resistance of the coating layer. Other relativelylight-stable isocyanates include some of the unsaturated isocyanates,particularly those that are araliphatic, including 1,2-, 1,3-, and1,4-xylene diisocyanates, m-tetramethylxylene diisocyanate,p-tetramethylxylene diisocyanate, uretdiones of toluene diisocyanates,isocyanurates of toluene diisocyanates, and isocyanurates ofdiphenylmethane diisocyanates.

[0033] In a preferred embodiment, the coating layer is formed from atwo-component polyurethane system in a single- or multi-solventdispersion having a medium to high solid content, with the percentage ofsolids by weight being greater than about 40% and by volume beinggreater than about 30%. The polyurethane coatings may be based on water,non-aqueous solvents, or combinations thereof. Non-aqueous systemstypically employ relatively high concentrations of one or more organicsolvents; water is generally excluded from the reaction environment.Organic solvents are expensive, hazardous (toxic and flammable), andundesirable especially for large-scale production. Therefore,water-borne coating systems are generally preferred.

[0034] Two-component, water-based polyurethane systems are preferablywater-reducible in that the addition of water does not increase thetendency of foaming of the coating. Such a coating layer may eliminatethe need for a primer coat or an adhesion promoting layer. Specificforms of aqueous coatings are aqueous solutions, emulsions, andcolloidal dispersions. In the aqueous solution (of resin), the resinused has a hydrophilic functional group; a curing agent is used exceptwhen the resin is a particular alkyd resin; and heating and drying athigh temperatures is necessary. In the emulsion and colloidaldispersion, ions, hydrophilic polymers, and low-molecular emulsifiersare adsorbed or absorbed onto a hydrophobic polymer; the coating filmformed has excellent water resistance and durability. For ease ofprocessing, the coating system may have a pot life of at least about 30minutes, preferably about 2 hours, and a curing temperature of about 25°C. to about 90° C. To achieve desirable impact resistance, abrasionresistance, and the like, the coating layer is preferably thermoset,formed from a reactive liquid material.

[0035] Suitable coating systems of the present invention may be based onmonomers and/or oligomers of acrylate, methacrylate, water/solvent-basedpolyurethane, epoxies, or combinations thereof. Weight percentage of thereactive monomers and/or oligomers may range from about 5% to about 95%of the total coating composition. Combinations of mono- and/ormulti-functional monomers and/or oligomers are desirable for highlycrosslinked coatings. Besides the initiators for the polymerizationreaction, the coating layers may further incorporate additionalreactants and additives known to one of ordinary skill in the art asbeing useful in other golf ball portions, such as the cover, the core,and the intermediate layer(s). For example, crosslinkers such aspolyfunctional aziridines may be used in an amount of about 10% or lessby weight of the total composition to promote adhesion to the substratelayer. UV absorbers, hindered amine light stabilizers, antioxidants, andoptical brighteners can be used alone or in combination of two or morethereof, in an amount of less than about 5% by weight, to improve lightstability and enhance aesthetic appeal. Other suitable reactants andadditives include, without limitation, olefins, acrylates, acrylics,polyols, polyamines, curing agents, catalysts, hardeners, thinners,pigments, and other modifying agents, incorporated in appropriateamounts to achieve their desired effects. Colorants, including tints andpigments, when present, are preferably white, but may be any othervisible color, or even fluorescent.

[0036] To improve uniformity, abrasion resistance, and/or weatherabilityof the coating layer, one or more fillers are selectively blended intothe coating composition. Suitable fillers include silica, clay, calciumcarbonate, and other finely powered inorganic fillers. Fillers such asZnO and TiO are preferred because they reflect the harmful UV light, andenhance light stability of the coating. Certain fillers exhibit highviscosity at low shear force, capable of preventing the coating fromcreeping around the dimples. Other fillers are particularly effective inenhancing abrasion resistance of the coating layer, such as colloidalsilica, which refers to silica in a single- or multi-solvent dispersion.The silica may be small spherical particles about 1 nm to about 200 nmin diameter, preferably about 50 nm to about 100 nm. Such nano-sizedsilica particles have refractive indices particularly suitable for clearcoatings; they pose limited scattering or interference to lighttransmission. The solvent is water for water-reducible coating systems,or one or more monomers or oligomers of ketones or alcohols for dualcure systems that use a combination of two or more curing means (e.g.,heating and UV irradiation). Suitable colloidal silica is eitheruntreated or surface-pretreated, such as Cab-O-Sil® by Cabot Corp. ofTuscola, Ill., Nyacol® 2040 by Nano Technologies of Ashland, Mass.,Hylink® OG by Clariant Corporation of Charlotte, N.C., and Snowtex® byNissan Chemical Industries of Tokyo, Japan. The colloidal silica istypically present in the coating material in an amount of at least about5 weight percent of the coating composition, preferably about 5 to about80 weight percent, more preferably about 10 to about 60 weight percent,and most preferably about 15 to about 30 weight percent. Colloidalsilica is distinct from solid silica such as hydrous silicic acid andsilicic anhydride. One or more organic or inorganic hard materialscapable of being triturated may be optionally incorporated into thecolloidal silica. The hard material preferably has a Mohs hardness of atleast about 5, and can be bound to the coating matrix through a couplingreaction. Suitable hard materials include, but are not limited to,silicates and oxides such as MgO, ZnO, or zirconium oxide. The hardparticles, when present, are in an amount of about 2 to about 25 weightpercent of the coating, in addition to the colloidal silica.

[0037] An optional coupling agent may be used to bond the filler to thepolymer matrix of the coating layer, to integrate the filler and keep itfrom sedimentation, and to promote adhesion and dispersion. Couplingagents are compounds having at least a first functionality linkable tothe filler particle, and at least a second functionality linkable to thecoating matrix or a reactive component therein. The first functionalgroup includes hydroxy, phenoxy, hydroxy ether, silane, or aminoplastmoieties. The second functional group includes hydroxy, isocyanate,carboxyl, epoxy, amine, urea, vinyl, amide, aminoplast, or silanemoieties. The coupling agent preferably has a polyvalent backbonecomprising one or more silicone or phosphorus moieties and alkyl groupshaving 1 to about 12 carbon atoms. Suitable coupling agents may beoligomeric or polymeric acrylics, polyesters, polyethers, polyurethanes,polyamides, epoxies, alkyds, or combinations of two or more thereof.Weight ratio of the coupling agent to the filler can be any amount thatwill result in the formation of a suitable abrasion resistant coating ona golf ball, preferably about 1:1 to about 1:90, more preferably about1:1 to about 1:40, and most preferably about 1:6 to about 1:12. Theweight ratio of colloidal silica/coupling agent combo to theresin/curative combo is preferably about 1:1 to about 1:50, morepreferably about 1:1 to about 1:10, and most preferably about 1:4 toabout 1:8.

[0038] Suitable coupling agents include silane coupling agents such asamine-functional silanes and acryloxy-functional silanes,carbamate-functional coupling agents, chromates, titanates, zirconium,zircoaluminate, polymeric coupling agents, and combinations of two ormore thereof. Preferred silane coupling agents have the formulaY(CH₂)_(n)SiX₃, where Y is an organofunctional group (e.g., asubstituted or unsubstituted aryl, alkyl or carbocyclic group) bondingthe polymer matrix to the central silicon atom via the stable (CH₂)_(n)carbon chain, and X is a silicon-functional or alkoxy group (e.g., OCH₃,OC₂H₅, OC₂H₄OCH₃) that hydrolyzes and subsequently reacts with activesites on inorganic surfaces. Exemplary silane coupling agents includeSilquest® A-174, A-1230, A-171, A-187, A-189, and A-1100 by OSiSpecialties, Danbury, Conn., and silanes Z-6011, Z-6020, Z-6030, andZ-6040 by Dow Corning Corporation of Midland, Mich. Titanate couplingagents include, for example, monoalkoxy titanate compounds, chelatetitanate compounds, quad titanate compounds, coordinate titanatecompounds, neoalkoxy titanate compounds, cycloheteroatom titanatecompounds, and those available from Du Pont Company of Wilmington, Del.Zirconium coupling agents include, for example, zircoaluminates,zirconium propionate, neoalkoxy zirconate, ammonium zirconium carbonate,and those available from Magnesium Elektron, Inc. of Flemington, N.J.Zircoaluminate coupling agents have both an aluminum and a zirconiumfunctional group in addition to an organic functionality. Mostpreferable coupling agents for the present invention are silane couplingagents, including aminosilanes, mercaptosilanes, glycidoxysilanes,epoxysilanes, methacryloxysilanes, vinylsilanes, alkoxysilane oligomers,nonionic silane dispersing agents, octyltriethoxysilane,methyltriethoxysilane, methyltrimethoxysilane, vinyltriethoxysilane,vinyltrimethoxysilane, vinyltris(2-methoxyethoxy)silane,γ-methacryloxypropyltrimethoxysilane,β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane,γ-aminopropyltriethoxysilane, aminoalkyl silicone solutions, modifiedaminoorganosilane, γ-aminopropyltrimethoxysilane, modifiedaminoorganosilane, β-(aminoethyl)-γ-aminopropyltrimethoxysilane,modified aminosilanes, triaminofunctional silanes, aminofunctionalsilanes, polyazamide silanes, γ-ureidopropyltriethoxysilane,isocyanatofunctional silanes; and mixtures thereof.

[0039] The coating layer of the present invention may be a clear orpigmented primer or topcoat, or a single layer combining the propertiesof both, formed onto a dimpled cover layer or outer cover layer throughany methods known to one of ordinary skill in the art. The formulationsare generally applied in a fluid form, providing a very thin coatinglayer, about 0.0001 inches to about 0.01 inches, about the outer coverlayer. Preferably, the thickness of the coating layer is about 0.001inches to about 0.01 inches; more preferably, about 0.002 inches toabout 0.005 inches. The amount of coating applied to a standard-sizedgolf ball of at least 1.68-inch in diameter is about 0.01 grams to about1 grams. Specific application techniques useful to form the coatinglayer include casting, spraying, dipping, spin coating, electrostaticcoating, flow coating, and others known to the skilled in the art. Thecoating layer may also be applied in a laminate form or by any othertechniques known in the art. Preferred methods of applying the coatingand reaction/coating conditions may vary with material compositions, butare well known to one of ordinary skill in the art. For instance, thecuring temperature for the coating compositions of the present inventionare preferably less than about 80° C., more preferably less than about60° C., and most preferably about 0° C. to about 50° C.

[0040] The coating compositions of the present invention and theirapplication in golf balls are further illustrated in the followingnon-limiting examples. Table I tabulates several polyurethane-basedcoating compositions provided by PPG Industries of Pittsburgh, Pa., withtheir respective averaged angles of friction (O) and COF calculatedtherefrom. TABLE I Coating Composition Averaged θ COF 60° Gloss Control(S24993) 31° 0.6 90 A (SB302-66A) 39° 0.81 4 B (SB302-66B) 51° 1.23 90 C(SB302-66C) 40° 0.84 6 D (SB302-66D) 51° 1.23 87 E (SB302-66E) 48° 1.1156

[0041] Experimental coating layers of the present invention, with athickness of about 0.001 inch to about 0.005 inch, is applied on golfballs commercially available from Acushnet Company of Fairhaven, Mass.The golf balls comprise a solid polybutadiene core of about 1.59 inchesin diameter and a Surlyn® ionomer-based cover layer of about 0.045 inchthick. Example groups Control and A through E used coating compositionsControl and A through E of Table I, respectively. Averaged spin ratesand corresponding launch angles of the example groups, each having atleast 9 golf balls, are tested with a standard driver at a speed ofabout 160 ft/sec, a full wedge at a speed of about 95 ft/sec, and a halfwedge at a speed of about 53 ft/sec. Results of these tests are listedin Table II below. TABLE II Driver Full Wedge Half Wedge Stimp Spin(rpm)/ Spin (rpm)/ Spin (rpm)/ Meter Launch Launch Launch Roll onExample Angle (°) Angle (°) Angle (°) Carpet (in) Control 2644/9.69370/25 5991/33 212.62 A 2840/9.3 4121/32 2605/41 206.79 B 2839/9.28595/26 5202/35 206.79 C 2923/9.1 4060/32 2488/41 208.29 D 2741/9.48054/27 4880/36 209.50 E 2618/9.6 6311/29 4348/37 209.04

[0042] While example groups A through E are all coated with a high COFcoating layer, their roll distances on carpet are about the same as thecontrol group. None of the high COF coating compositions A through Balters the driver spin or the associated launch angle by more than 15%.The largest increase in driver spin rate, as observed in example group Cin comparison with the control group, is less than 11%. However, thesame high COF coating compositions consistently influence the spin ratesand corresponding launch angles of the example golf balls off the fullwedge and the half wedge. Specifically, the full wedge and half wedgespin rates of groups A through E are reduced comparing to the controlgroup, while the full wedge and half wedge launch angles are elevated atthe same time. The high COF coating layer of the present inventionpreferably reduces the golf ball's full wedge spin rate and/or halfwedge spin rate by at least about 5%, more preferably by at least about10%, and most preferably about 15% to about 80%. Relatively smalleffects of the high COF coating layer are observed in example group B,which shows a spin reduction of about 8% and a launch angle elevation ofabout 10 when struck with a full wedge, and a spin reduction of about13% and a launch angle elevation of about 2° when struck with a halfwedge. Relatively large effects of high COF coating layer are observedin example group C, which shows a spin reduction of about 57% and alaunch angle elevation of about 7° when struck with a full wedge, and aspin reduction of about 58% and a launch angle elevation of about 8°when struck with a half wedge. These empirical data seem to indicate thepresence of an optimal COF value at which the spin reduction and thelaunch angle elevation are maximized. This optimal COF appears to liesomewhere between 0.8 and 1.

[0043] The coating layer of the present invention is relatively soft butdurable, suitable for applications in sporting equipment in general.Preferably, the coating layer is used on golf equipment, including, butnot limited to, golf balls; golf clubs (i.e., putters, drivers, andwedges) and club attachments, additions, or modifications, such asstriking face inserts, back cavity of an iron-type club, crown or soleof a metal wood-type club; golf club components (i.e., shafts, hosels,and grips); golf club vibration damping devices; golf gloves andportions thereof, such as glove liners, securing methods, patches, andreinforcements; golf shoes and associated components (i.e., soles,footbeds and spike socket spines, heel counters, toe “puffs,” uppers,insoles, midsoles, outsoles, liners, and plastic golf spikes); golf bagsand their associated framework, support legs, and stands; and anyportion of the above items. When used on an outermost surface of a golfball or a club face, substantially all of the coating layer remainsadhered thereto after repeated impact between the golf ball and the clubface, preferably at least about 90 weight percent remains, morepreferably at least about 95 weight percent, and most preferably atleast about 99 weight percent.

[0044] Golf balls of the present invention may have a variety ofconstructions, comprising at least a core, a cover, and one or moreoptional intermediate layers disposed between the core and the cover.The core may be a single solid mass, or include a center and one or moreouter core layers. The center may further be solid, liquid-filled,gel-filled, or gas-filled. The cover may include an outer cover layerand, optionally, one or more inner cover layers. Any of the outer corelayers, the intermediate layers, or the inner cover layers may be acontinuous layer, a discontinuous layer, a wound layer, a molded layer,a lattice network layer, a web or net, an adhesion or coupling layer, abarrier layer, a layer of uniformed or non-uniformed thickness, a layerhaving a plurality of discrete elements such as islands or protrusions,a solid layer, a metallic layer, a liquid-filled layer, a gas-filledlayer, or a foamed layer.

[0045] The coating layer as described above is preferably disposed on orabout a golf ball cover. The cover may comprise a single layer, or anouter cover layer and one or more inner cover layer(s). The cover layer,particularly the outer cover layer, of the present invention maycomprise about 1 weight percent to about 100 weight percent, preferablyabout 5 weight percent to about 95 weight percent, of an ethylene/acidionomer, a grafted or non-grafted metallocene-catalyzed polymer, or athermoplastic or thermoset reaction product.

[0046] The reaction product is preferably formed from a liquid reactivematerial. More preferably, the reaction product is a polyurethane,polyurea, or polyurethane/polyurea hybrid comprising a polyahl, anisocyanate, and an optional curing agent. The polyahls are preferablyincorporated into one or more soft segments of the reaction product.Suitable polyahls such as polyols and polyamines are organic, modifiedorganic, saturated, aliphatic, alicyclic, unsaturated, araliphatic,aromatic, substituted, unsubstituted, or ionomeric, having two or morereactive hydrogen groups per molecule, such as primary or secondaryhydroxy groups or amine groups. The isocyanate-reactive hydroxy and/oramine groups may be terminal or pendant groups on the oligomeric orpolymeric backbone, and in the case of secondary amine groups, may evenbe embedded within the backbone.

[0047] Any isocyanate available to one of ordinary skill in the art issuitable for use according to the invention. The isocyanate may beorganic, modified organic, saturated, aliphatic, alicyclic, unsaturated,araliphatic, aromatic, substituted, or unsubstituted diisocyanate orpolyisocyanate monomers having two or more free reactive isocyanate(“NCO”) groups; isomers thereof; modified derivatives thereof; dimersthereof; trimers thereof; or isocyanurates thereof. The isocyanate mayalso include any isocyanate-terminated multimeric adducts, oligomers,polymers, prepolymers, low-free-monomer prepolymers, quasi-prepolymers,and modified polyisocyanates derived from the isocyanates andpolyisocyanates above. Low-free-monomer prepolymers refer to prepolymershaving free isocyanate monomer levels less than about 0.5 weightpercent. Curing agents are monomeric, oligomeric, or polymeric compoundsused in cover compositions for chain-extension and/or crosslink.Suitable curing agents for the invention include polyahls and epoxies,preferably hydroxy curatives, amine curatives, and amino alcoholcuratives having a molecular weight of about 50 to about 5,000.

[0048] For best light stability, all reactants in the polyurethane orpolyurea compositions, including the polyahl(s), the isocyanate(s), andthe curing agent(s) are substantially saturated. A hindered secondarydiamine having a high level of stearic hindrance may be used tobeneficially slow down the curing process. A variety of additives canoptionally be incorporated into the cover layer compositions of thepresent invention in amounts sufficient to achieve their specificpurposes and desired effects. Suitable additives include, but are notlimited to, catalysts such as dibutyltin dilaurate, UV absorbers,hindered amine light stabilizers, antioxidants, accelerators, fillers,viscosity modifiers, release agents, plasticizers, compatibilizingagents, coupling agents, dispersing agents, colorants including pigmentsand dyes, optical brighteners, surfactants, lubricants, stabilizers,metals, processing aids or oils, blowing agents, freezing pointdepressants, and any other modifying agents known to one of ordinaryskill in the art.

[0049] Other cover useful materials for the present invention include:

[0050] 1) Non-ionomeric acid polymers, such as copolymers E/Y of anolefin E having 2 to 8 carbon atoms and a carboxylic acid Y having 3 to8 carbon atoms, or terpolymers E/X/Y having an additional softeningcomonomer X. The olefin E is preferably ethylene, and the acid Yincludes acrylic, methacrylic, crotonic, maleic, fumaric, or itaconicacid. The comonomer X includes vinyl esters of aliphatic carboxylicacids having 2 to 10 carbon atoms, and alkyl ethers, alkyl acrylates, oralkyl alkylacrylates of alkyl groups having 1 to 10 carbon atoms.Depending on the acid content by weight, the polymer may be referred toas low-acid (about 2% to less than 10%), medium-acid (about 10% to lessthan 16%), and high-acid (about 16% to about 50%). The comonomer, whenpresent, may be in an amount of about 2% to about 40% by weight of theacid polymer. Preferred non-ionomeric acid polymers include Nucrel® fromE. I. DuPont de Nemours & Company and Escor® from ExxonMobil.

[0051] 2) Anionic and cationic ionomers such as the acid polymers abovepartially or fully neutralized with organic or inorganic cations, suchas zinc, sodium, lithium, magnesium, potassium, calcium, manganese,nickel, ammonium (primary, secondary, tertiary), or the like. The extentof saturation ranges from about 5% to about 110%, preferably at leastabout 50%, more preferably at least about 70%. Preferred acid ionomersinclude Surlyn® from E. I. DuPont de Nemours & Company and Iotek® fromExxonMobil.

[0052] 3) Thermoplastic or thermoset (vulcanized) synthetic or naturalrubbers, including polyolefins and copolymers or blends thereof, such asbalata, polyethylene, polypropylene, polybutylene, isoprene rubber,ethylene-propylene rubber, ethylene-butylene rubber,ethylene-propylene-(non-conjugated diene) terpolymers; polystyrenes andcopolymers thereof, such as styrene-butadiene copolymers,poly(styrene-co-maleic anhydride), acrylonitrile-butylene-styrenecopolymers, poly(styrene sulfonate); and homopolymers or copolymersproduced using single-site catalyst such as metallocene (grafted ornon-grafted).

[0053] 4) Polyphenylene oxide resins, polyarylene ethers, or blends ofpolyphenylene oxide with high impact polystyrene such as Noryl® fromGeneral Electric Company.

[0054] 5) Thermoplastics, including polyesters, such as ethylenemethylacrylate, ethylene ethylacrylate, ethylene vinyl acetate,poly(ethylene terephthalate), poly(butylene terephthalate),poly(propylene terephthalate), poly(trimethylene terephthalate),modified poly(ethylene terephthalate)/glycol, poly(ethylenenaphthalate), cellulose esters, Hytrel® from E. I. DuPont de Nemours &Company, and Lomod® from General Electric Company; polycarbonates;polyacetals; polyimides; polyetherketones; polyamideimides;thermoplastic block copolymers (Kraton® rubbers from Shell Chemical);co-polyetheramides (Pebax® from AtoFina); and elastomers in general.

[0055] 6) Vinyl resins such as polyvinyl alcohols, polyvinyl alcoholcopolymers, polyvinyl chloride, block copolymers of alkenyl aromaticswith vinyl aromatics and polyesteramides, copolymers of vinyl chloridewith vinyl acetate, acrylic esters or vinylidene chloride.

[0056] 7) Polyamides such as poly(hexamethylene adipamide) and othersprepared from diamines, fatty acids, dibasic acids, and amino acids(poly(caprolactam)), and blends of polyamides with Surlyn®, ethylenehomopolymers or copolymers or terpolymers, etc.

[0057] 8) Acrylic resins and blends of these resins with polyvinylchloride or other elastomers.

[0058] 9) Blends and alloys, including blends of polycarbonate andacrylonitrile-butylene-styrene, blends of polycarbonate andpolyurethane, blends of polyvinyl chloride withacrylonitrile-butadiene-styrene or ethylene vinyl acetate or otherelastomers, blends of thermoplastic rubbers with polyethylene orpolypropylene.

[0059] The cover layer preferably has a flexural modulus of at leastabout 2,000 psi, a material hardness between about 20 Shore D and about75 Shore D, and a hardness as measured on the ball of less than about 80Shore D. In one embodiment, the cover layer has a Shore D hardness ofabout 30 to about 60 and a flexural modulus of about 10,000 psi to about80,000 psi. A thin cover layer with a thickness of about 0.01 inches toabout 0.04 inches is preferred for players with high swing speeds, whilea relatively thick cover layer of greater than 0.04 inches to about 0.08inch, more preferably about 0.05 inches to about 0.07 inch, is preferredfor players with moderate swing speeds. In a preferred embodiment, thecover thickness is 0.03 inches or less.

[0060] While it is preferred that the golf ball be encapsulated in acoating layer as described above, it is possible to have a golf ballwithout the coating layer. In this embodiment, the outermost surface ofthe golf ball is comprised of a cover material having the desired highCOF and other properties as the coating layer described above. Thisoutermost surface may be the outer surface of a single-layered cover, orthe outer surface of an outer cover layer in a golf ball cover thatcomprises the outer cover layer and one or more inner cover layers.

[0061] Any method known to one of ordinary skill in the art may be usedto produce the cover layer of the present invention. One-shot methodinvolving concurrent mixing of the isocyanate, the polyether polyahl,and the curing agent is feasible, but the resulting mixture isnon-homogenous and difficult to control. The prepolymer method describedabove is most preferred, because it affords a more homogeneous mixtureresulting in a more consistent polymer composition. The prepolymer maybe reacted with a diol or a secondary diamine to form a thermoplasticmaterial, or reacted with a triol, tetraol, primary diamine, triamine,or tetramine to form a thermoset material. Other methods suitable forforming the layers include casting, compression molding, reactioninjection molding (“RIM”), liquid injection molding (“LIM”),injection-compression molding, pre-reacting the components to form aninjection moldable thermoplastic material and then injection molding,and combinations thereof, such as RIM/compression molding,injection/compression molding, progressive compression molding, and thelike. Thermoplastic formulations may be processed using any number ofcompression or injection molding techniques. Thermoset formulations maybe castable, reaction injection moldable, sprayable, or applied in alaminate form or by any techniques known in the art. Castable reactiveliquid materials such as polyurea, polyurethane, andpolyurethane/polyurea hybrid can provide very thin layers such as outercover layers that are desirable on golf balls. Other techniques includespraying, dipping, spin coating, or flow coating methods.

[0062] An optional intermediate layer may be disposed between the coreand the cover, preferably between the cover and the optional barrierlayer. The intermediate layer may be part of the cover as an inner coverlayer, formed from non-ionomeric acid polymers or ionomeric derivativesthereof, polyamides, polyolefins, polyurethanes, polyureas, epoxies,polyethers, polyesters, polyetheresters such as Hytrel® from DuPont,polyetheramides such as Pebax® from AtoFina, nylons,metallocene-catalyzed polymers, styrenic block copolymers such asKraton® from Shell Chemicals, acrylonitrile-butadiene-styrene copolymers(“ABS”), polyvinyl chlorides, polyvinyl alcohol copolymers,polycarbonates, polyesteramides, polyamides, polyimides,polyetherketones, polyamideimides, silicones, metal salts of fattyacids, and combinations thereof, such as blends of polycarbonate andacrylonitrile-butadiene-styrene, blends of polycarbonate andpolyurethane. Two or more of these materials may be blended together toform the intermediate layer.

[0063] The intermediate layer may incorporate a modulus-enhancing filleror a density-modifying filler to attain preferred physical andmechanical properties. The composition of the intermediate layer mayhave a modulus of about 2,000 psi to about 150,000 psi, a materialhardness of about 60 Shore C to about 80 Shore D, and a thickness ofabout 0.005 inches to about 0.6 inch. The composition of theintermediate layer may be applied as a liquid, powder, dispersion,lacquer, paste, gel, melt, or solid half shells. The intermediate layermay be formed around the core or onto the inside of the cover by sheetstock or vacuum shrink-wrapping, compression molding, injection molding,vacuum deposition, RIM, lamination, casting, spraying, dipping, powdercoating, or any other deposition means. Preferably, a combination ofthese methods is used, such as injection/compression molding,RIM/compression molding, pre-form/compression molding, injectionmolding/grinding, injection/progressive compression molding,co-injection molding, or simplified casting of a single block material.

[0064] The golf ball core is preferably solid and made from any suitablecore materials including thermosets such as natural rubber,polybutadiene, polyisoprene, styrene-butadiene orstyrene-propylene-diene rubber, and thermoplastics such as ionomerresins, polyamides, polyesters, or a thermoplastic elastomer. The corecan also be formed from a castable material such as polyurethanes,polyureas, epoxies, silicones, etc. Preferred compositions for solidcores include a base rubber, a crosslinking agent, and an initiator. Apreferred base rubber is 1,4-polybutadiene having a cis-bond of at leastabout 40%, a Mooney viscosity of at least about 30, a molecular weightof at least about 150,000, and a polydispersity of less than about 4.Examples of desirable polybutadiene rubbers include Buna® CB22 and CB23from Bayer, Ubepol® 360 L and 150 L from Ube Industries, Cariflex®BCP820 and BCP824 from Shell Chemical, and Kinetix® 7245 and 7265 fromGoodyear. Blends of two or more such polybutadienes are desirable forthe solid cores. In one embodiment, a cobalt or nickel catalyzedpolybutadiene having a Mooney viscosity of from about 50 to about 150 ismixed with a neodymium catalyzed polybutadiene having a Mooney viscosityof from about 30 to about 100. The weight ratio between the twopolybutadienes may range between about 5:95 and 95:5. The polybutadienecan also be mixed with other elastomers known in the art, such asnatural rubber, polyisoprene rubber and/or styrene-butadiene rubber, inorder to modify the properties of the core.

[0065] Suitable cross-linking agents for the polybutadiene-based solidcores include metal salts of unsaturated fatty acid having 3 to 8 carbonatoms, such as zinc diacrylate, zinc dimethacrylate, and blends thereof.The crosslinking agent is typically present in an amount of about 15parts to about 60 parts per 100 parts by weight of the base polymer. Theinitiator includes organic peroxide compounds, such as dicumyl peroxide,and azo initiators. The initiators are present in an amount of about 0.5part to about 2.5 parts per 100 parts by weight of the base polymer. Ahalogenated organosulfur compound such as pentachlorothiophenol (“PCTP”)or ZnPCTP is blended into the base polymer to further enhance thesoftness and resiliency of the core. The halogenated organosulfurcompound is present in an amount of about 0.1 part about 2 parts, oralternatively, about 2 parts to about 5 parts per 100 parts by weight ofthe base polymer. The solid core may also include fillers such astungsten powder and zinc oxide to adjust hardness, strength, modulus,weight, density and/or specific gravity of the core. Other optionaladditives include antioxidants, accelerators, processing aids or oils,cis-to-trans catalysts, coupling agents, stable free radicals, radicalscavangers, scorch retarders, and blends thereof, used in amountssufficient to achieve their specific purposes and desired effects.

[0066] The core of the golf ball of the present invention has a diameterof at least about 0.5 inch. In one embodiment, the core diameter is atleast about 1 inch, more preferably from about 1.5 inches to about 1.65inches, and most preferably from about 1.55 inches to about 1.6 inches.The core may have a compression of from about 20 to about 120, morepreferably from about 30 to about 100, and most preferably from about 40to about 80. Alternatively, the core may be very soft, with acompression of less than about 20. The core should also be highlyresilient, having a COR of at least about 0.75, preferably at leastabout 0.8. Conventional methods and techniques may be used to form thesolid cores from the base compositions disclosed herein.

[0067] The golf ball of the present invention as described abovepreferably has a COR of greater than about 0.79, a compression of lessthan about 110, and a deflection at 100 kg of greater than about 1.5 mm.The golf ball preferably has an overall diameter of at least about 1.68inches, more preferably from about 1.68 inches to about 1.76 inches. Atleast 60% of the outermost surface of the golf ball is covered by about250 to about 450 dimples of equal or different shape and size. Preferreddimple patterns involving catenary curves, and preferred lift and dragcharacteristics of the golf ball of the present invention are disclosedin co-pending U.S. application Ser. Nos. 09/989,191 and 10/096,852,respectively, both incorporated herein by reference in their entirety.

[0068] Preferred golf ball constructions for the present inventioninclude a core, a cover, and a coating layer disclosed herein disposedonto the cover. The core is a one-piece solid sphere formed of apolybutadiene or a blend of two or more polybutadienes with Mooneyviscosity of greater than about 35, an initiator, and a ZDA level ofabout 15 phr or greater. Alternatively, the core is a dual core formedof a center and an outer core layer disposed about the center. Thecenter includes a polybutadiene or a blend of two or more polybutadieneswith Mooney viscosity of greater than about 35, an initiator, and a ZDAlevel of about 15 phr to about 40 phr. The center may furtherincorporate a regrind or filler such as tungsten metal powder. Thecenter has a diameter of about 0.5 inches to about 1.6 inches. The outercore layer includes a polybutadiene or a blend of two or morepolybutadienes with Mooney viscosity of greater than about 35, aninitiator, and a ZDA level of about 25 phr to about 55 phr. The outercore layer may further incorporate a regrind, a polyisoprene such asbalata, or a filler such as tungsten metal powder. Optionally, thesingle-piece core, the center, or the outer core layer can incorporateZnPCTP. The core has a diameter of less than about 1.64 inches,preferably about 1.5 inches to about 1.6 inches, more preferably about1.55 inches to about 1.59 inches. The core has a compression of lessthan about 100, preferably about 20 to about 80, more preferably about30 to about 70. The core also has a specific gravity of less than about1.4 g/cm³, a deflection at 100 kg of greater than about 1.5 mm, and aCOR of greater than about 0.75. An optional barrier layer with a MVTR ofless than that of a Surlyn® by DuPont may be applied over the core. Thecover is formed of a blend of metallocene-catalyzed polymers andethylene/acid ionomers, having a material hardness of about 25 Shore Dto about 65 Shore D, a flexural modulus of greater than about 2,000 psi,and a thickness of about 0.03 inches to about 0.07 inches. Dimplecoverage over the cover is greater than about 70%, with about 350 toabout 450 dimples, preferably in an icosahedron design. The golf ballhas a compression of about 60 to about 80, and a coefficient ofrestitution of greater than about 0.79.

[0069] All patents and patent applications cited in the foregoing textare expressly incorporated herein by reference in their entirety.

[0070] The invention described and claimed herein is not to be limitedin scope by the specific embodiments herein disclosed, since theseembodiments are intended solely as illustrations of several aspects ofthe invention. Any equivalent embodiments and various modificationsapparent to those skilled in the art are intended to be within the scopeof this invention. It is further understood that the various features ofthe present invention can be used singly or in combination thereof. Suchmodifications and combinations are also intended to fall within thescope of the appended claims.

1. A golf ball comprising a core and a cover, wherein an outermostsurface of the golf ball has a high coefficient of friction of greaterthan 0.6, wherein the outermost surface is formed of a coating layercomprising a two-component system including a polymer having at leastone isocyanate-reactive functionality and an isocyanate and wherein thecoating layer has a Sward hardness of less than about
 20. 2. The golfball of claim 1, wherein the coefficient of friction is about 0.8 toabout 1.5.
 3. The golf ball of claim 1, wherein the outermost surfacehas a 60° gloss of at least about
 3. 4. The golf ball of claim 1,wherein the outermost surface has a 60° gloss of about 80 to about 95.5. The golf ball of claim 1, wherein the outermost surface ishydrophobic.
 6. The golf ball of claim 1, wherein the coating layer hasa thickness of about 0.0001 inches to about 0.01 inches.
 7. The golfball of claim 6, wherein the coating layer is translucent, transparent,or pigmented.
 8. (Cancelled).
 9. The golf ball of claim 6, wherein thecoating layer has a Sward hardness of less than about
 10. 10. The golfball of claim 6, wherein the coating layer has a Sward hardness of lessthan about
 5. 11. A golf ball comprising a core and a cover, wherein anoutermost surface of the golf ball has a high coefficient of friction ofgreater than 0.6 wherein the outermost surface is formed of a coatinglayer having a thickness of about 0.0001 inches to about 0.01 inches andwherein the coating layer is formed from a two-component thermosetpolyurethane.
 12. The golf ball of claim 11, wherein the polyurethane issubstantially saturated.
 13. The golf ball of claim 11, wherein thepolyurethane comprises a UV absorber, a hindered amine light stabilizer,an antioxidant, an optical brightener, a coupling agent, or acombination thereof.
 14. The golf ball of claim 6, wherein the coatinglayer has a solid content by weight of at least about 40%.
 15. The golfball of claim 6, wherein the coating layer has a cross hatch adhesion ofabout 90% to about 100%.
 16. (Cancelled).
 17. The golf ball of claim 1,wherein the cover comprises at least one of a metallocene-catalyzedpolymer, an ethylene/acid ionomer, a thermoplastic or thermosetpolyurethane, or a thermoplastic or thermoset polyurea.
 18. A golf ballcomprising a core and a cover, wherein an outermost surface of the golfball has a high coefficient of friction of greater than 0.6 and whereinthe golf ball does not have a coating layer such that the outermostsurface of the golf ball is an outer surface of the cover.
 19. A golfball comprising a core, a cover, and a first coating layer with a highcoefficient of friction of at least about 0.7 disposed about the cover,wherein the golf ball exhibits, in comparison to a second golf ballcomprising a second coating layer with a second coefficient of frictionof 0.6, a spin rate change of less than about 15% when struck with astandard driver at a speed of about 160 ft/sec.
 20. The golf ball ofclaim 19, wherein the coefficient of friction of the coating layer isabout 0.8 to about 1.5.
 21. The golf ball of claim 19, wherein thecoating layer has a 60° gloss of at least about
 50. 22. The golf ball ofclaim 19, wherein the coating layer has a 60° gloss of about 80 to about95.
 23. The golf ball of claim 19, wherein the golf ball, when struckwith a full wedge at a speed of about 95 ft/sec, has an elevated launchangle and a spin rate reduction of at least about 5% in comparison tothe second golf ball.
 24. The golf ball of claim 19, wherein the golfball has an elevated launch angle and a spin rate reduction of at leastabout 10% when struck with a half wedge at a speed of about 53 ft/sec,in comparison to the second golf ball. 25-27. (Cancelled).